The negative temperature coefficient of pyrethroid action will be examined in the nervous system of house flies to determine the basis for the temperature dependence of toxicity. The actions of pyrethroids on the peripheral sensory and motor neurons will be investigated to determine their contribution to poisoning. The nature of burst discharges of nervous impulses produced during pyrethroid poisoning will be compared to nervous activity produced by DDT analogs in an effort to define the differences between DDT and pyrethroid mode of action. Sublethal damage from insecticide treatment will be examined in house flies to determine the nature of nervous impairment from insecticide poisoning.